Stub in more IPC attachment brokering functionality.

ipc/brokerable_attachment.cc

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ipc/brokerable_attachment.h"
 
+#include <limits>
+
+#include "base/rand_util.h"
+
 namespace IPC {
 
-BrokerableAttachment::BrokerableAttachment() {
+namespace {
+
+BrokerableAttachment::AttachmentId GetRandomId() {
+  BrokerableAttachment::AttachmentId id;
+  for (int i = 0; i < 4; ++i) {
+    id.nonce[i] = base::RandInt(std::numeric_limits<int>::min(),

[Tom Sepez, 2015/06/19 18:04:10]

Does this need to be unguessable?  If so, you need a routine from crypto/
instead of this.

[Tom Sepez, 2015/06/19 18:04:11]

nit: signed to unsigned assignment.  Maybe the nonce is uint8_t[16] and use
RandBytes().

[erikchen, 2015/06/23 22:37:00]

Yes it does. I've switched to crypto::RandBytes.

[erikchen, 2015/06/23 22:37:00]

Good suggestion, done.

+                                std::numeric_limits<int>::max());
+  }
+  return id;
+}
+
+}  // namespace
+
+BrokerableAttachment::BrokerableAttachment() : id_(GetRandomId()) {
 }
 
 BrokerableAttachment::~BrokerableAttachment() {
 }
 
 BrokerableAttachment::AttachmentId BrokerableAttachment::GetIdentifier() const {
   return id_;
 }
 
+BrokerableAttachment::Type BrokerableAttachment::GetType() const {
+  return TYPE_BROKERABLE_ATTACHMENT;
+}
+
 }  // namespace IPC